IPM for Controlling Rodents

Control in Hay and Pasture

Glenn Shewmaker

and Danielle Gunn

POPULATION CONTROL

• Develop an integrated approach based on knowledge

of:

– the animal's ecology and behavior

– information on all available control techniques.

• Using an integrated pest management (IPM) program

will result in an environmentally and economically

acceptable approach that will significantly reduce

damage to alfalfa crops.

Thresholds

• Threshold levels for rodents and other vertebrate

pests in alfalfa are not generally established.

• Experiences of growers give us some ideas about

when and if control measures should be taken.

MEADOW VOLES

Microtus pennsylvanicus most common

• Damage alfalfa and grasses by feeding on roots and

stems.

• They are small rodents with heavy bodies, short legs

and tails, and small, rounded ears. Their coarse fur is

blackish brown to grayish brown in color.

• When full grown, they are 4 to 5 inches long.

House mouse

(Mus musculus)

MEADOW VOLES

• Active all year

• Normally found in areas with

dense ground cover.

• They dig short, shallow burrows

and make underground nests of

grass, stems, and leaves.

Meadow Vole Control

• Remove or reduce the

vegetative cover

• Initiate a program of

habitat modification

and/or population

reduction before their

numbers explode

Trapping

• In a small area, trapping may be effective

– The simple, wooden mousetrap is used. Bait with

peanut butter, oatmeal, or apple slices

– Often, no bait is needed because voles will trigger the

trap as they pass over it. Voles seldom stray from their

usual travel routes.

– Place traps at right angles to and flush with the ground

in these runways.

Trapping

• A trap line of 50-100 traps should be used.

• Examine traps daily.

• Remove and bury dead voles.

• Do not handle dead voles without gloves.

• Restrictions on trapping animals in Washington!

Toxic Baits

When meadow voles are numerous or when damage

occurs over large areas:

• Take care to ensure the safety of children, pets, and

non-target animals.

• Do this by following product label instructions

carefully.

Idaho Pesticide Product Registrations

http://ww.kellysolutions.com/ID

• For information on endangered species:

www.epa.gov/oppfead1/endanger/bulletins.htm

PROZAP® ZINC

PHOSPHIDE OAT BAIT

Endangered Species

Considerations

• Whooping Crane (Grus americana)

– Do not use this product in habitats

occupied or occasionally visited by

whooping cranes during the period

from 30 days before the expected

arrival of cranes to 30 days after the

time of their usual departure.

• Black-footed Ferret (Mustela

nigripes)

– Do not use this product within 7

kilometers (4.34 miles) of any prairie

dog town to limit risks to the black-

footed ferret from exposure to Zinc

Phosphide or destruction of its prey

base, unless . . . . .

PROZAP® ZINC

PHOSPHIDE OAT BAIT

Endangered Species Considerations• Gray Wolf (Canis lupus) and Grizzly Bear (Ursus actos horribilus)

– Unless the local U.S. Fish and Wildlife Service office has determined that

there are no gray wolves or grizzly bears in the general vicinity of bait

applications in Montana and Wyoming, do not apply this product outdoors

within occupied habitat of these species.

• Northern Idaho Ground Squirrel (Spermophilus brunneus

brunneus)

– Do not use this product within 0.5 miles in critical habitat of the Northern

Idaho Ground Squirrel in Adams and Valley counties, Idaho.

• VOLES in Alfalfa

• USE RESTRICTIONS: For control of meadow voles, long-

tailed voles, California voles, Oregon voles, mountain voles

and Townsend’s voles (Microtus spp.) in alfalfa. All

applications must occur shortly after a cutting of the hay,

and/or prior to the next growth’s attaining a length of 2 inches.

Alfalfa forage from treated areas must not be harvested until it

reaches maturity.

• This use is restricted to Montana, California, Idaho, Oregon,

and Washington.

Prozap® Zinc Phosphide Oat Bait

Page 12 of 17

April 20th, 2015

PROZAP® ZINC PHOSPHIDE OAT BAIT

• VOLES in Alfalfa

• BROADCAST BAITING: This product may be broadcast by

air or ground-driven dispensing devices.

• Apply at a rate of up to 10 lbs. per acre (0.2 lb. ai/A).

• For voles, make two applications per year separated by a

minimum interval of 25 days.

• A maximum of 20 lbs per acre (0.4 lb ai/A) may be applied per

year.

• Do not apply by air when wind velocity exceeds 10 mph. Do

not apply in piles or permit piles to be formed by equipment.

Prozap® Zinc Phosphide Oat Bait

Page 12 of 17

April 20th, 2015

PROZAP® ZINC PHOSPHIDE OAT BAIT

VOLES in Timothy and Timothy / Alfalfa Mixtures For Hay:

• Do not apply by air. Do not apply to actively growing timothy or

timothy/alfalfa mixtures. This use is restricted to California,

Idaho, Oregon and Washington.

• Do not apply to timothy or timothy/alfalfa mixtures within

60 days of harvest.

• BROADCAST BAITING: Broadcast bait using by hand, cyclone

seeder, or ground-driven dispensing devices. A maximum of 2

applications by ground may be made at the rate of 5 to 10 lbs.

per acre (0.1-0.2 lb ai/A), one in the fall after the last cutting and

one in the spring when timothy and timothy-legume mixtures

are still dormant. Do not apply in piles or permit piles to be

formed by equipment. A maximum of 20 lbs (0.4 lb ai/A) per

acre may be applied annually.

Prozap® Zinc Phosphide Oat Bait

Page 12 of 17

April 20th, 2015

PROZAP® ZINC PHOSPHIDE OAT BAIT

Zinc Phosphide Cautions

• DO NOT GET IT WET!

– Moisture activates the chemical, rendering it ineffective

very quickly.

• Not many crops are labeled—mostly non-crop land,

ditch banks, pastures, and orchards.

• Alfalfa, barley, beans, timothy sugar beets, and

wheat are labeled for bait applications.

FOLLOW-UP:

• Using waterproof gloves, collect and properly dispose

of all dead animals and excess bait properly in

accordance with “Pesticide Disposal” instructions.

• Use detergent and hot water to wash spoons for

application into burrows.

• Do not use spoon for mixing, holding or transferring

food or feed.

• To discourage re-infestation, limit sources of rodent

food, water, and harborage as much as possible.

USES ASSOCIATED WITH AGRICULTURAL

SITES

Use Restrictions for all Agricultural Sites

• Do not apply this product in a way that will contact workers or

other persons, either directly or through drift.

• Only protected handlers may be in the area during application.

• Keep all other persons out of the treated area during this

application.

• Do not apply on roads, near residential areas, or over water.

• Do not broadcast over crops unless use directions specifically

permit aerial application.

• Apply bait on warm clear days.

Zinc phosphide

• Should not be used in the same field more that once

in a 6 month period.

• Rapid acting. You may find dead voles within 12

hours of baiting.

• When practical (e.g. dead voles in the open such as

along roads), dispose of dead voles by burying.

Non-target Effects of Zinc Phosphide

• Does not accumulate in the tissue of voles

• predators or scavengers (dogs and cats) are not

likely to be affected by eating the poisoned rodents.

• However, children, as well as pets, birds, and other

animals, can be affected by the bait,

• so store it out of reach and use it carefully in a way

that will minimize their access to it.

• Zinc phosphide is a Restricted Use Material.

Multiple-feeding baits

• Anticoagulant baits are registered for meadow vole

control but not for use in alfalfa crops.

• Use in areas adjacent to the alfalfa field or during

crop dormancy or where contact with the alfalfa plant

will not occur.

Multiple-feeding baits

• Slow acting and must be consumed over a period of

days to be effective.

• Whole grain baits are commonly recommended,

• but pelleted baits are also available.

• Moisture-resistant paraffin block baits are useful

around ditches and other areas where high moisture

may cause other types of baits to spoil.

Multiple-feeding baits

• Because voles must feed on anticoagulant baits over

a period of days, the bait must be available until the

population is controlled.

• Bait placement is very important.

• Place it in runways or next to burrows so voles will

find it during their normal travel.

Multiple-feeding baits

• Anticoagulants were registered for in-crop use in

2011 with a 24-C application to Idaho Dept. of Ag.

Multiple-feeding baits

• Some anticoagulant paraffin bait blocks are

registered for voles.

• Bait blocks should not be used where children or pets

might pick them up.

Bait Station

Diagrams by Sherman Takatori

Pocket Gophers

Thomomys species, are

burrowing rodents that

get their name from the

fur-lined, external cheek

pouches, or pockets,

they use for carrying

food and nesting

materials.

Pocket Gophers

•Well equipped for a digging.

•Seldom seen.

•Crescent-shaped mounds.

Photo Credits: Dallas Virchow

Pocket Gophers

• For the most part, gophers remain underground in

their burrow system, although you’ll sometimes see

them feeding at the edge of an open burrow, pushing

dirt out of a burrow, or moving to a new area.

• Gophers form mounds as they dig tunnels and push

the loose dirt to the surface.

• Typically mounds are crescent or horseshoe shaped

when viewed from above.

BIOLOGY AND BEHAVIOR

• Burrow system can

cover 200 to 2,000 ft2

• 2.5 to 3.5 inches in

diameter.

• Feeding burrows are 6 to

12 inches below ground,

and the nest and food

storage chamber can be

as deep as 6 feet.

Probing for Burrows

• Locate areas of recent gopher

activity based on fresh mounds

of dark, moist soil.

• Fresh mounds that are visible aboveground are

the plugged openings of lateral tunnels.

• Find the main burrow by probing about 8 to 12

inches from the plug side of the mound; it

usually is located 6 to 12 inches deep. http://elkhorn.unl.edu/epublic/pages/publicationD.jsp?publicationId=72

Probing for Burrows

• When the probe penetrates the

gopher’s burrow, there will be a sudden,

noticeable drop of about 2 inches.

• The gopher might not revisit lateral

tunnels, trapping and baiting them is not

as successful as in the main burrow.

Bait Options

• Strychnine

– Harsh on Primary/Secondary

– NO above ground use

• Anticoagulants

– Slower Acting, Thorough

• Zinc Phosphide

– Fast Acting, Gases off in contact with moisture,

Bird toxicity issues

Trapping

• Safe and effective method for controlling pocket

gophers.

• A popular type is the choker-style box trap.

Setting Traps

• Locate the main tunnel with a probe, as described

above.

• Use a shovel to open the tunnel wide enough to set

traps in pairs facing opposite directions.

• Placing traps with their openings facing in opposite

directions means you will be able to intercept a

gopher coming from either end of the burrow.

• 20 to 60 % success depending on trap

Trap Types

Cinch

Blackhole

Macabee

0

5

10

15

20

25

30

35

40

45

Blackhole Macabee Cinch

Harvest Efficiency

Baiting with Toxic Baits

• Always place pocket gopher bait in the main

underground tunnel, not the lateral tunnels.

• After locating the main gopher tunnel with a probe,

enlarge the opening by rotating the probe or inserting

a larger rod or stick.

• Following label directions, place the bait carefully in

the opening using a spoon or other suitable

implement that you use only for that purpose, taking

care not to spill any onto the ground.

Strychnine Hand Bait

• Good control for:

– Small outbreaks

– Garden areas

http://www.agri.state.id.us/Categories/Pesticides/registration/indexregistrationmain.php

Toxins

• Strychnine-treated grain is the most common type of

bait used for pocket gopher control.

• This bait generally contains 0.5% strychnine and is

lethal with a single feeding.

• Baits containing 2.0% zinc phosphide are also

available.

• As with strychnine, these baits are lethal after a

single feeding.

PROZAP® ZINC PHOSPHIDE OAT BAIT

ALFALFA, LAWNS, GOLF COURSES,

OTHER NONCROP AREAS

USE RESTRICTIONS:

For control of the

following pocket

gophers: Plains

(Geomys bursarius), . . .

, and Thomomys spp, in

subterranean

applications only.

ZP AG OATS

ALFALFA

USE RESTRICTIONS: For control of meadow voles,

long-tailed voles, California

voles, Oregon voles, mountain

voles and Townsend’s voles (Microtus spp.) and Richardson’s

ground squirrels (Spermophilus richardsonii) in alfalfa.

All applications must occur shortly after a cutting of the hay, and/or

prior to the next growth’s attaining a length of 2 inches. Alfalfa

forage from treated areas must not be harvested until it reaches

maturity. This use is restricted to Montana, California, Idaho,

Oregon, and the state of Washington.

ALFALFA

PREBAITING: When bait is to be used to control

Richardson’s ground squirrels, prebaiting with

untreated steamed crimped oats at a rate of 6 lbs. per

acre 2-3 days before ZP AG OATS is applied is likely to

enhance acceptance of the toxic bait.

Multiple feeding anticoagulants

• You’ll need to set out a large amount of bait—about

10 times the amount needed when using strychnine

baits—so enough will be available for multiple

feedings.

• Although generally less effective than strychnine

baits, anticoagulant baits are less toxic.

• After placing the bait in the main tunnel, close the

probe hole with sod, rocks, or some other material

that excludes light while preventing dirt from falling on

the bait.

• Several bait placements within a burrow system will

increase success.

• Tamp down or clear existing mounds, so you can

distinguish new activity.

The Burrow Builder Applicator

Improperly formed burrow

The Correct Operation of BB

Rozol® Pocket Gopher Bait – Burrow

Builder Formula

• Restricted-Use Product.

• Now Approved for use on Alfalfa!

• Approved for use in the states of:

AR, CA, CO, ID, KS, MT, NE, NV, NM, ND, OK, OR,

SD, TX, UT, WA, WI, WY

• EPA Reg. No. 7173-244

Rozol® Pocket Gopher Bait – Burrow

Builder Formula

• Apply when soil conditions allow

formation of good artificial burrows.

• Make artificial burrows at the same depth

as natural burrows, perpendicular and

about 20-30 ft. apart.

• Apply at 6-8 lbs. per acre, picking up any

spilled bait. See entire label.

Rodenator

• Rodent Pest Control

- Killing Rodents @

Rodenator

• http://www.rodenator.

com

Explosive Method

• Oxygen and acetylene

PERC

• Pressurized Exhaust

Rodent Controller

systems available from

H & M Gopher Control

• http://www.handmgoph

ercontrol.com/

Words of Caution

• ALWAYS read and follow the instructions printed on

the pesticide label.

• The pesticide recommendations in this UI

presentation do not substitute for instructions on the

label.

• Pesticide laws and labels change frequently and may

have changed since this publication was written.

Words of Caution

• Some pesticides may have been withdrawn or had

certain uses prohibited. Use pesticides with care.

• Do not use a pesticide unless the specific plant,

animal, or other application site is specifically listed

on the label.

• Store pesticides in their original containers and keep

them out of the reach of children, pets, and livestock.

Words of Caution

• Trade Names--To simplify information, trade names

have been used.

• No endorsement of named products is intended nor

is criticism implied of similar products not mentioned.

• Groundwater--To protect groundwater, when there is

a choice of pesticides, the applicator should use the

product least likely to leach.

Resources: